Pub Date : 2025-02-13DOI: 10.1515/nanoph-2024-0457
Karl J. McNulty, Shriddha Chaitanya, Swarnava Sanyal, Andres Gil-Molina, Mateus Corato-Zanarella, Yoshitomo Okawachi, Alexander L. Gaeta, Michal Lipson
Silicon nitride (SiN) formed via low pressure chemical vapor deposition (LPCVD) is an ideal material platform for on-chip nonlinear photonics owing to its low propagation loss and competitive nonlinear index. Despite this, LPCVD SiN is restricted in its scalability due to the film stress when high thicknesses, required for nonlinear dispersion engineering, are deposited. This stress in turn leads to film cracking and makes integrating such films in silicon foundries challenging. To overcome this limitation, we propose a bilayer waveguide scheme comprised of a thin LPCVD SiN layer underneath a low-stress and low-index PECVD SiN layer. We show group velocity dispersion tuning at 1,550 nm without concern for film-cracking while enabling low loss resonators with intrinsic quality factors above 1 million. Finally, we demonstrate a locked, normal dispersion Kerr frequency comb with our bilayer waveguide resonators spanning 120 nm in the c-band with an on-chip pump power of 350 mW.
通过低压化学气相沉积（LPCVD）形成的氮化硅（SiN）具有低传播损耗和极具竞争力的非线性指数，是片上非线性光子学的理想材料平台。尽管如此，由于沉积非线性色散工程所需的高厚度薄膜时会产生薄膜应力，因此 LPCVD SiN 的可扩展性受到限制。这种应力反过来又会导致薄膜开裂，使得在硅代工厂中集成这种薄膜具有挑战性。为了克服这一限制，我们提出了一种双层波导方案，即在低应力、低指数的 PECVD SiN 层下有一层薄的 LPCVD SiN 层。我们展示了 1550 纳米波长下的群速度色散调谐，无需担心薄膜开裂，同时实现了本征品质因数超过 100 万的低损耗谐振器。最后，我们利用双层波导谐振器在 c 波段 120 nm 范围内展示了锁定的正常色散克尔频率梳，片上泵功率为 350 mW。
{"title":"Overcoming stress limitations in SiN nonlinear photonics via a bilayer waveguide","authors":"Karl J. McNulty, Shriddha Chaitanya, Swarnava Sanyal, Andres Gil-Molina, Mateus Corato-Zanarella, Yoshitomo Okawachi, Alexander L. Gaeta, Michal Lipson","doi":"10.1515/nanoph-2024-0457","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0457","url":null,"abstract":"Silicon nitride (SiN) formed via low pressure chemical vapor deposition (LPCVD) is an ideal material platform for on-chip nonlinear photonics owing to its low propagation loss and competitive nonlinear index. Despite this, LPCVD SiN is restricted in its scalability due to the film stress when high thicknesses, required for nonlinear dispersion engineering, are deposited. This stress in turn leads to film cracking and makes integrating such films in silicon foundries challenging. To overcome this limitation, we propose a bilayer waveguide scheme comprised of a thin LPCVD SiN layer underneath a low-stress and low-index PECVD SiN layer. We show group velocity dispersion tuning at 1,550 nm without concern for film-cracking while enabling low loss resonators with intrinsic quality factors above 1 million. Finally, we demonstrate a locked, normal dispersion Kerr frequency comb with our bilayer waveguide resonators spanning 120 nm in the c-band with an on-chip pump power of 350 mW.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"21 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1515/nanoph-2024-0682
Diana Serrano, Nao Harada, Romain Bachelet, Anna Blin, Alban Ferrier, Alexey Tiranov, Tian Zhong, Philippe Goldner, Alexandre Tallaire
Thin films provide nanoscale confinement together with compatibility with photonic and microwave architectures, making them ideal candidates for chip-scale quantum devices. In this work, we propose a thin film fabrication approach yielding the epitaxial growth of Eu3+ doped Y2O3 on silicon. We combine two of the most prominent thin film deposition techniques: chemical vapor deposition (CVD) and molecular beam epitaxy (MBE). We report sub-megahertz optical homogeneous linewidths up to 8 K for the Eu3+ dopants in the film, and lowest value of 270 kHz. This result constitutes a ten-fold improvement with respect to previous reports on the same material, opening promising perspectives for the development of scalable and compact quantum devices containing rare-earth ions.
{"title":"Sub-MHz homogeneous linewidth in epitaxial Y2O3: Eu3+ thin film on silicon","authors":"Diana Serrano, Nao Harada, Romain Bachelet, Anna Blin, Alban Ferrier, Alexey Tiranov, Tian Zhong, Philippe Goldner, Alexandre Tallaire","doi":"10.1515/nanoph-2024-0682","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0682","url":null,"abstract":"Thin films provide nanoscale confinement together with compatibility with photonic and microwave architectures, making them ideal candidates for chip-scale quantum devices. In this work, we propose a thin film fabrication approach yielding the epitaxial growth of Eu<jats:sup>3+</jats:sup> doped Y<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> on silicon. We combine two of the most prominent thin film deposition techniques: chemical vapor deposition (CVD) and molecular beam epitaxy (MBE). We report sub-megahertz optical homogeneous linewidths up to 8 K for the Eu<jats:sup>3+</jats:sup> dopants in the film, and lowest value of 270 kHz. This result constitutes a ten-fold improvement with respect to previous reports on the same material, opening promising perspectives for the development of scalable and compact quantum devices containing rare-earth ions.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"63 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1515/nanoph-2024-0644
Quentin Saudan, Dagmawi A. Bekele, Meng Xiong, Kresten Yvind, Michael Galili, Jesper Mørk
We propose and experimentally demonstrate a small-mode volume bowtie cavity design for all-optical switching applications using a waveguide-cavity structure that exploits asymmetric Fano resonance lineshapes. The bowtie cavity has a mode volume that is five times smaller than conventional (H0-type) photonic crystal point-defect cavities enabling higher nonlinearity and faster switching. Blue and red-detuned Fano resonant devices based on bowtie cavity designs have been fabricated and characterized. Measured linear transmission spectra have been compared to coupled-mode theory models to extract key parameters such as Q-factors. Furthermore, all-optical switching at 2.5 Gbps have been demonstrated in a wavelength-conversion experiment.
{"title":"All-optical switch exploiting Fano resonance and subwavelength light confinement","authors":"Quentin Saudan, Dagmawi A. Bekele, Meng Xiong, Kresten Yvind, Michael Galili, Jesper Mørk","doi":"10.1515/nanoph-2024-0644","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0644","url":null,"abstract":"We propose and experimentally demonstrate a small-mode volume bowtie cavity design for all-optical switching applications using a waveguide-cavity structure that exploits asymmetric Fano resonance lineshapes. The bowtie cavity has a mode volume that is five times smaller than conventional (H0-type) photonic crystal point-defect cavities enabling higher nonlinearity and faster switching. Blue and red-detuned Fano resonant devices based on bowtie cavity designs have been fabricated and characterized. Measured linear transmission spectra have been compared to coupled-mode theory models to extract key parameters such as Q-factors. Furthermore, all-optical switching at 2.5 Gbps have been demonstrated in a wavelength-conversion experiment.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"16 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1515/nanoph-2024-0577
Stuart Love, Mohamad Hossein Idjadi, Farshid Ashtiani, Howard (Ho-Wai) Lee, Andrea Blanco-Redondo
In the past decade, the field of topological photonics has gained prominence exhibiting consequential effects in quantum information science, lasing, and large-scale integrated photonics. Many of these topological systems exhibit protected states, enabling robust travel along their edges without being affected by defects or disorder. Nonetheless, conventional topological structures often lack the flexibility for implementing different topological models and for tunability postfabrication. Here, we present a method to implement magnetic-like Hamiltonians supporting topologically protected edge modes on a general-purpose programmable silicon photonic mesh of interferometers. By reconfiguring the lattice onto a two-dimensional mesh of ring resonators with carefully tuned couplings, we show robust edge state transport even in the presence of manufacturing tolerance defects. We showcase the system’s reconfigurability by demonstrating topological insulator lattices of different sizes and shapes and introduce edge and bulk defects to underscore the robustness of the photonic edge states. Our study paves the way for the implementation of photonic topological insulators on general-purpose programmable photonics platforms.
{"title":"A programmable platform for photonic topological insulators","authors":"Stuart Love, Mohamad Hossein Idjadi, Farshid Ashtiani, Howard (Ho-Wai) Lee, Andrea Blanco-Redondo","doi":"10.1515/nanoph-2024-0577","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0577","url":null,"abstract":"In the past decade, the field of topological photonics has gained prominence exhibiting consequential effects in quantum information science, lasing, and large-scale integrated photonics. Many of these topological systems exhibit protected states, enabling robust travel along their edges without being affected by defects or disorder. Nonetheless, conventional topological structures often lack the flexibility for implementing different topological models and for tunability postfabrication. Here, we present a method to implement magnetic-like Hamiltonians supporting topologically protected edge modes on a general-purpose programmable silicon photonic mesh of interferometers. By reconfiguring the lattice onto a two-dimensional mesh of ring resonators with carefully tuned couplings, we show robust edge state transport even in the presence of manufacturing tolerance defects. We showcase the system’s reconfigurability by demonstrating topological insulator lattices of different sizes and shapes and introduce edge and bulk defects to underscore the robustness of the photonic edge states. Our study paves the way for the implementation of photonic topological insulators on general-purpose programmable photonics platforms.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"51 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1515/nanoph-2024-0513
Grigorii Slinkov, Steven Becker, Dirk Englund, Birgit Stiller
Optical neural networks have demonstrated their potential to overcome the computational bottleneck of modern digital electronics. However, their development towards high-performing computing alternatives is hindered by one of the optical neural networks’ key components: the activation function. Most of the reported activation functions rely on opto-electronic conversion, sacrificing the unique advantages of photonics, such as resource-efficient coherent and frequency-multiplexed information encoding. Here, we experimentally demonstrate a photonic nonlinear activation function based on stimulated Brillouin scattering. It is coherent and frequency selective and can be tuned all-optically to take LeakyReLU, Sigmoid, and Quadratic shape. Our design compensates for the insertion loss automatically by providing net gain as high as 20 dB, paving the way for deep optical neural networks.
{"title":"All-optical nonlinear activation function based on stimulated Brillouin scattering","authors":"Grigorii Slinkov, Steven Becker, Dirk Englund, Birgit Stiller","doi":"10.1515/nanoph-2024-0513","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0513","url":null,"abstract":"Optical neural networks have demonstrated their potential to overcome the computational bottleneck of modern digital electronics. However, their development towards high-performing computing alternatives is hindered by one of the optical neural networks’ key components: the activation function. Most of the reported activation functions rely on opto-electronic conversion, sacrificing the unique advantages of photonics, such as resource-efficient coherent and frequency-multiplexed information encoding. Here, we experimentally demonstrate a photonic nonlinear activation function based on stimulated Brillouin scattering. It is coherent and frequency selective and can be tuned all-optically to take L<jats:sc>eaky</jats:sc>R<jats:sc>e</jats:sc>LU, S<jats:sc>igmoid</jats:sc>, and Q<jats:sc>uadratic</jats:sc> shape. Our design compensates for the insertion loss automatically by providing net gain as high as 20 dB, paving the way for deep optical neural networks.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"9 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143417691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1515/nanoph-2024-0746
Minghao Ning, Haozong Zhong, Zhen Gu, Ling-En Zhang, Ning Qu, Jun Ding, Tao Li, Lin Li
Optical encryption offers a powerful platform for secure information transfer, combining low power consumption, high-speed transmission, and intuitive visualization. Metasurfaces, with their unprecedented ability to manipulate light across multiple degrees of freedom within quasi-two-dimensional nanostructures, are emerging as promising devices for advanced encryption. However, encryption capacity remains constrained by limited information channels. Here, we present a visual secret sharing (VSS) scheme utilizing metasurfaces with multiple polarization-dependent channels and minimized crosstalk. Using a global optimization strategy for nanostructure geometries across the entire metasurface, we successfully realize eight independent polarization channels with negligible crosstalk. By encoding both the key and information into these channels with a modified VSS scheme, we demonstrate the complete recovery of seven plaintexts. This strategy supports scalable, high-capacity encryption, and can incorporate additional optical degrees of freedom, offering advanced solutions for advanced secure communication, information storage, and anti-counterfeiting.
{"title":"Enhanced optical encryption via polarization-dependent multi-channel metasurfaces","authors":"Minghao Ning, Haozong Zhong, Zhen Gu, Ling-En Zhang, Ning Qu, Jun Ding, Tao Li, Lin Li","doi":"10.1515/nanoph-2024-0746","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0746","url":null,"abstract":"Optical encryption offers a powerful platform for secure information transfer, combining low power consumption, high-speed transmission, and intuitive visualization. Metasurfaces, with their unprecedented ability to manipulate light across multiple degrees of freedom within quasi-two-dimensional nanostructures, are emerging as promising devices for advanced encryption. However, encryption capacity remains constrained by limited information channels. Here, we present a visual secret sharing (VSS) scheme utilizing metasurfaces with multiple polarization-dependent channels and minimized crosstalk. Using a global optimization strategy for nanostructure geometries across the entire metasurface, we successfully realize eight independent polarization channels with negligible crosstalk. By encoding both the key and information into these channels with a modified VSS scheme, we demonstrate the complete recovery of seven plaintexts. This strategy supports scalable, high-capacity encryption, and can incorporate additional optical degrees of freedom, offering advanced solutions for advanced secure communication, information storage, and anti-counterfeiting.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"8 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1515/nanoph-2024-0721
Timon Eichhorn, Nicholas Jobbitt, Sören Bieling, Shuping Liu, Tobias Krom, Diana Serrano, Robert Huber, Ulrich Lemmer, Hugues de Riedmatten, Philippe Goldner, David Hunger
Europium-doped nanocrystals constitute a promising material for a scalable future quantum computing platform. Long-lived nuclear spin states could serve as qubits addressed via coherent optical transitions. In order to realize an efficient spin-photon interface, we couple the emission from a single nanoparticle to a fiber-based microcavity under cryogenic conditions. The spatial and spectral tunability of the cavity permits us to place individual nanoparticles in the cavity, to measure the inhomogeneous linewidth of the ions, and to show a multi-modal Purcell-enhancement of two transition in Eu3+. A halving of the free-space lifetime to 1.0 ms is observed, corresponding to a 140-fold enhancement of the respective transition. Furthermore, we observe a narrow optical linewidth of 3.3 MHz for a few-ion ensemble in the center of the inhomogeneous line. The results represent an important step towards the efficient readout of single Eu3+ ions, a key requirement for the realization of single-ion-level quantum processing nodes in the solid state.
{"title":"Multimodal Purcell enhancement and optical coherence of Eu3+ ions in a single nanoparticle coupled to a microcavity","authors":"Timon Eichhorn, Nicholas Jobbitt, Sören Bieling, Shuping Liu, Tobias Krom, Diana Serrano, Robert Huber, Ulrich Lemmer, Hugues de Riedmatten, Philippe Goldner, David Hunger","doi":"10.1515/nanoph-2024-0721","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0721","url":null,"abstract":"Europium-doped nanocrystals constitute a promising material for a scalable future quantum computing platform. Long-lived nuclear spin states could serve as qubits addressed via coherent optical transitions. In order to realize an efficient spin-photon interface, we couple the emission from a single nanoparticle to a fiber-based microcavity under cryogenic conditions. The spatial and spectral tunability of the cavity permits us to place individual nanoparticles in the cavity, to measure the inhomogeneous linewidth of the ions, and to show a multi-modal Purcell-enhancement of two transition in Eu<jats:sup>3+</jats:sup>. A halving of the free-space lifetime to 1.0 ms is observed, corresponding to a 140-fold enhancement of the respective transition. Furthermore, we observe a narrow optical linewidth of 3.3 MHz for a few-ion ensemble in the center of the inhomogeneous line. The results represent an important step towards the efficient readout of single Eu<jats:sup>3+</jats:sup> ions, a key requirement for the realization of single-ion-level quantum processing nodes in the solid state.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"8 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1515/nanoph-2024-0764
Hsiao-Chih Huang, Kefu Mu, Hui Min Leung, Chen-Ting Liao
Intra-system entanglement occurs between non-separable modes within the same system. For optical systems, the various degrees of freedom of light represent different modes, and the potential use of light to create higher dimensional classical entangle states offers a promising potential to drive new technological developments. In this work, we present experimental results demonstrating the orthogonality between transverse orbital angular momentum (t-OAM) of different spatiotemporal topological charges, a previously unverified property of t-OAM. Based on those results, we developed methods to create and characterize a novel family of t-OAM and polarization entangled spatiotemporal structured light. We further provide theoretical analysis to support our study of the entanglement between those modes. By demonstrating the feasibility of leveraging t-OAM as a new family of modes for classical entanglement, our work represents a new advancement towards higher dimensional classical entanglement strategies.
{"title":"Transverse orbital angular momentum and polarization entangled spatiotemporal structured light","authors":"Hsiao-Chih Huang, Kefu Mu, Hui Min Leung, Chen-Ting Liao","doi":"10.1515/nanoph-2024-0764","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0764","url":null,"abstract":"Intra-system entanglement occurs between non-separable modes within the same system. For optical systems, the various degrees of freedom of light represent different modes, and the potential use of light to create higher dimensional classical entangle states offers a promising potential to drive new technological developments. In this work, we present experimental results demonstrating the orthogonality between transverse orbital angular momentum (t-OAM) of different spatiotemporal topological charges, a previously unverified property of t-OAM. Based on those results, we developed methods to create and characterize a novel family of t-OAM and polarization entangled spatiotemporal structured light. We further provide theoretical analysis to support our study of the entanglement between those modes. By demonstrating the feasibility of leveraging t-OAM as a new family of modes for classical entanglement, our work represents a new advancement towards higher dimensional classical entanglement strategies.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"78 3 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1515/nanoph-2024-0728
Ning Li, He Chen, Yunxia Zhao, Yongtian Wang, Zhaoxian Su, Yin Liu, Lingling Huang
The quasi-bound state in the continuum (quasi-BIC) of dielectric metasurface provides a crucial platform for sensing, because its almost infinite Q-factor can greatly enhance the interactions between light waves and the analytes. In this work, we proposed an ultrasensitive all-dielectric metasurface sensor composed of periodic rectangular amorphous silicon pillars on a quartz substrate. By breaking symmetry of two pillars in unit cell, high Q quasi-BIC in the continuous near-infrared band can be excited. The magnetic toroidal dipole (MTD) is demonstrated to play a dominating role in the resonant modes by analyzing near-field distribution and multipole decomposition. The asymmetry degree has a significant impact on sensing performance of the proposed metasurface sensor, whose underlying physical mechanisms is analyzed by perturbation theory. The transmission spectrum and sensing performance of the fabricated metasurface sensor were measured. The experimental results show our designed metasurface sensor not only achieve a high sensitivity of 413/RIU, but also shows a high figure of merit (FOM) of 66 RIU−1. This work provides excellent prospects for the excitation of strong MTD resonance quasi-BIC in sensing applications.
{"title":"Ultrasensitive metasurface sensor based on quasi-bound states in the continuum","authors":"Ning Li, He Chen, Yunxia Zhao, Yongtian Wang, Zhaoxian Su, Yin Liu, Lingling Huang","doi":"10.1515/nanoph-2024-0728","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0728","url":null,"abstract":"The quasi-bound state in the continuum (quasi-BIC) of dielectric metasurface provides a crucial platform for sensing, because its almost infinite <jats:italic>Q</jats:italic>-factor can greatly enhance the interactions between light waves and the analytes. In this work, we proposed an ultrasensitive all-dielectric metasurface sensor composed of periodic rectangular amorphous silicon pillars on a quartz substrate. By breaking symmetry of two pillars in unit cell, high <jats:italic>Q</jats:italic> quasi-BIC in the continuous near-infrared band can be excited. The magnetic toroidal dipole (MTD) is demonstrated to play a dominating role in the resonant modes by analyzing near-field distribution and multipole decomposition. The asymmetry degree has a significant impact on sensing performance of the proposed metasurface sensor, whose underlying physical mechanisms is analyzed by perturbation theory. The transmission spectrum and sensing performance of the fabricated metasurface sensor were measured. The experimental results show our designed metasurface sensor not only achieve a high sensitivity of 413/RIU, but also shows a high figure of merit (FOM) of 66 RIU<jats:sup>−1</jats:sup>. This work provides excellent prospects for the excitation of strong MTD resonance quasi-BIC in sensing applications.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"95 4 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1515/nanoph-2024-0565
Juwon Jung, Nagyeong Kim, Kibaek Kim, Jongkyoon Park, Yong Jai Cho, Won Chegal, Young-Joo Kim
Accurate and fast characterization of nanostructures using spectroscopic ellipsometry (SE) is required in both industrial and research fields. However, conventional methods used in SE data analysis often face challenges in balancing accuracy and speed, especially for the in situ monitoring on complex nanostructures. Additionally, optical constants are so crucial for accurately predicting structural parameters since SE data were strongly related to them. This study proposes a three-step algorithm designed for fast and accurate extraction of structural parameters from SE measurements. The method utilizes three neural networks, each trained on simulation data, to obtain optical constants and progressively refine the prediction on structural parameters at each step. When tested on both simulation and measurement data on the fabricated 1D SiO2 nanograting specimen, the algorithm demonstrated both high accuracy and fast analysis speed, with average mean absolute error (MAE) of 0.103 nm and analysis speed of 132 ms. Also, the proposed algorithm shows more flexibility in accounting for any change of optical constants to serve as a more efficient solution in the real-time monitoring.
{"title":"Neural network-based analysis algorithm on Mueller matrix data of spectroscopic ellipsometry for the structure evaluation of nanogratings with various optical constants","authors":"Juwon Jung, Nagyeong Kim, Kibaek Kim, Jongkyoon Park, Yong Jai Cho, Won Chegal, Young-Joo Kim","doi":"10.1515/nanoph-2024-0565","DOIUrl":"https://doi.org/10.1515/nanoph-2024-0565","url":null,"abstract":"Accurate and fast characterization of nanostructures using spectroscopic ellipsometry (SE) is required in both industrial and research fields. However, conventional methods used in SE data analysis often face challenges in balancing accuracy and speed, especially for the <jats:italic>in situ</jats:italic> monitoring on complex nanostructures. Additionally, optical constants are so crucial for accurately predicting structural parameters since SE data were strongly related to them. This study proposes a three-step algorithm designed for fast and accurate extraction of structural parameters from SE measurements. The method utilizes three neural networks, each trained on simulation data, to obtain optical constants and progressively refine the prediction on structural parameters at each step. When tested on both simulation and measurement data on the fabricated 1D SiO<jats:sub>2</jats:sub> nanograting specimen, the algorithm demonstrated both high accuracy and fast analysis speed, with average mean absolute error (MAE) of 0.103 nm and analysis speed of 132 ms. Also, the proposed algorithm shows more flexibility in accounting for any change of optical constants to serve as a more efficient solution in the real-time monitoring.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"62 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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